Project Summary The goal of this mentored career training grant is to provide the candidate with the skills, time, and resources necessary to develop into an independent scientist. This will be accomplished through coursework in genomic sequencing, bioinformatics, dermatology, leadership, grantsmanship, and presentation skills. The candidate has assembled a scientific team with expertise in dermatology, immunology, and cutting-edge genomic sequencing techniques for the successful achievement of the proposal's specific aims and candidate's training. In addition, the candidate has a long-standing interest in immunology at mucocutaneous surfaces, and the focus of this proposal is to understand the immune responses that initiate atopic dermatitis skin inflammation. Atopic dermatitis (AD) is an itchy, chronic inflammatory skin disorder that affects 15-30% of children and 5% of adults in the U.S.. Although the precise etiology of AD is unclear, it is associated with a complex interaction of epidermal barrier defects (such as filaggrin loss-of-function mutations), mechanical injury from scratching, dysbiosis, Th2 and recently Th17 and Th22 responses. However, a fundamental unanswered immunological question in AD is how skin injury, such as induced by scratching, drives chronic inflammation. Therefore, we developed a filaggrin-deficient mouse model to examine the immune responses that contribute to injury-induced AD skin inflammation. Guided by strong preliminary data, we will test our central hypothesis that in the setting of filaggrin deficiency TLR activation up-regulates keratinocyte nuclear IL-1? expression, and upon skin injury, nuclear IL-1? is released to promote pro-inflammatory gene expression and IL-17 and IL-22 T cell responses that drive chronic AD-like skin inflammation. Therefore, the objective of this proposal is to: Aim 1.) Determine the role of bacterial sensing TLRs in stimulating keratinocyte IL-1? expression. Mice will be treated with TLR agonists or antagonists to elucidate the contribution of TLRs to dysregulated IL-1?. Aim 2.) Determine the functional role of nuclear IL-1? in keratinocytes under homeostasis and inflammation. The IL-1? -DNA binding sites will be identified by ChIP-seq analysis in homeostatic and inflamed keratinocytes and gene expression of the identified sites examined by qPCR. Aim 3.) Determine the contribution to inflammation of IL-17 and IL-22 T cells derived from microbial-induced keratinocyte IL-1? release. The role of the skin microbiota and IL-1? in IL-17 and IL-22 T cell development will be tested in mice given Neosporin or neutralizing anti-IL-1? mAb, or the contribution of IL-17 and IL-22 T cell responses to skin inflammation tested with antibody blockade of IL-17 and IL-22. This proposal is innovative because it investigates novel immune processes that promote AD skin inflammation. This work is significant because it will identify new immune pathways that may serve as therapeutic targets against AD skin inflammation.